The invention relates to efficiently performing hash join with large dimension tables. More specifically, the invention efficiently performs star join queries that reference large dimension tables.
A fact table is the central table in a star schema of a data warehouse. The fact table stores quantitative information for analysis and works with dimension tables. A fact table holds data to be analyzed, and a dimension table stores data about the ways in which the data in the fact table can be analyzed. Accordingly, dimension tables contain attributes that describe fact records in the fact table.
A star schema is a data warehousing schema that consists of one or more fact tables referencing any number of dimension tables. SQL queries to star schemas are accomplished with inner joins between the fact table and its dimension tables, also known as a star join. The star join is constrained by memory, and as such a star join for a large dimension table is prohibitive.